Phonograph reproducer



Dec. 27, 1938.

L. THOMPSON ET AL PHONOGRAPH REPRODUCER 2 Sheets-Sheet 1 Filed Apr il 17, 1936 I INVENTORS mm L 62 no .LIN 6 6 B Y ATTORNEY Dec. 27, 1938. THOMSON 5+ AL 4 PHONOGRAPH REPRODUCER Filed April 17, 1936 2 Sheets-Sheet 2 INVENTORS Lmcoln Thompson Egbert Lfitane fir ATTORNZ s Patented 15..., 1938 PATENTOFFICE 2,141,804 I PHONOGRAPH asrnonnonn.

Lincoln Thompson and Robert L. Stone,

Cheshire, Conn.

Application April 17, 1936, Serial No. 74,919

10 Claims.

This invention relates to phonograph repro ducing devices, and more particularly to a low inertia and low pressure reproducer especially adapted for the playing of soft records, such as aluminum or wax, with permanent needles of sapphire, steel or other hard material.

One object of this invention is to provide a device of the above nature employing a relatively long light weight reproducer arm'and a light weight pick-up, and in which said pickup is flexibly mounted on a horizontal pivot at the end of said arm, whereby the mechanical impedance or moment of inertia of the pick-up around a horizontal axis is reduced.

A further object is to provide a device of the above nature in which the reproducer arm is mounted to swing on a vertical ball-bearing spindle so as to reduce the horizontal friction of the reproducer arm.

A further object is to provide a device of the above nature having an auxiliary stop arm 10- cated under and adapted to support the weight of the reproducer arm. J

A still further object isto provide a device of the above nature in which means are provided for permitting the reproducer arm. and needlecarrying pick-up supported thereby to be raised away from the record whenever desired, and also having means for automatically replacing the needle. upon the recordany desired number of grooves (within limits) behind the original position of said needle.

A still further object is to provide adjustable spring means mounted on the reproducer arm for engaging the pick-up to press the needle positively upon the record, and thus take up play or slackf; insuring proper tracking and avoiding grooveq'umping, said spring means also increasing the ability of the pick-up to rapidly follow depressions in the recordgrooves, which occur when the record wobbles due to warping or eccentricity.

Still a further object is to provide a phonographic pick-up employing a relatively long light weight rigid stiff needle adapted to efllciently' transmit the mechanical undulations received at the needle point to the electrical amplifying apparatus.

A further object is to provide an apparatus of the above nature which will be simple in construction, inexpensive to manufacture, easy to install and manipulate, compact, ornamental in appearance, and very efllcient and durable in use.

with these and other objects in view, there have been illustrated on the accompanying draw.- ings, two forms in which the invention maybe conveniently embodied in practice.

In the drawings:

Fig. 1 represents a plan view of the disc record m phonograph reproducer, showing a diagrammatic view of the electrical circuit connections.

Fig. 2 is a sidev elevation of the reproducer arm, with certain parts broken away to show the interior construction.

Fig. 3 is a side elevation, partly in section, of the cam mechanism for lifting the reproducer arm and back spacing the reproducing needle, the view being taken along the line 3-3 of Fig. 2.

Fig. 4 is atransverse sectional view of the com- 15 mutator switch for automatically stopping the cam driving motor, the view taken along the line 4-4 of Fig. 3.

Fig. 5 is a transverse sectional view of the lifting cam mechanism taken along the line 5-5 of 20 Fig. 3, the cam being at an intermediate position.

Fig. 6 is a sectional view of an alternative form of automatic motor stopping switch, and showing the cam in itsj riormal inactive low position.

In the playing or reproducing of disc records of soft material, such as aluminum and wax, it was formerly necessary to employ fragile wooden or thorn needles, as otherwise, the records would wear out too rapidly on account ofthe abrasive and indenting action of hard needles caused by the high pressures exerted thereon by the heavy high-inertia pick-up head and reproducer arm'. Such wooden and thorn needles were found objectionable as they were quite delicate, and the points would wear off quickly and often break, causing unfaithful reproduction.'

By means of the present invention, the above disadvantages have been overcome, and it is now possible to reduce the pressure exerted on the 40 record by the needle to the order of one-tenth of an ounce, which has been found to be a pressure which will not harm the surface of aluminum or other soft records now in general use. Even the lightest of the pick-ups previously usedexerted at least two ounces pressure on the record, and many pick-ups employed pressures as high as five ounces, causing excessive wear and indentaupon the record. Moreover, the pick-up mem-' ber oscillates up and down on a very short axis, and hence,- can rapidly follow the up and down wobbles of the turntable .and record. Sudden bumps in the record will not materially increase the needle pressure, but the latter will remain practically constant under all ordinary condir tions.

Referring now to the drawings in which like reference numerals denote corresponding parts throughout the several views, the numeral is indicates the top panel of the motor cabinet, above which is positioned a turntable II for supporting a disc record l2. The turntable I l is supported by a vertical pindle I 3 passing upwardly through the panel It, said spindle being driven by a suitable electric motor l4 mounted under said panel l- Pivoted on both horizontal and verticalaxes at one corner of the panel III is an elongated reproducer radial arm l5, preferably constructed of light material, such as Duralumimin the form ofas a U-shaped channel.

Pick-up member I The outer free end of the reproducer arm 18 carries a pick-up member II. The pick-up member l8 is provided with a suitable socket for detachably receiving a stylus or needle I! having a rounded or other shaped point to fit the groove in the record and detachably held in place by a set screw The needle is preferably made maengage in a pair of sockets in an ear 40 projecttively long and of light strong stiff material. It is also provided with a hard point. preferably of sapphire or steel, for contacting with the grooved surface of the record.

opposed pointed screws l9 adJustably threaded into a pair of. side wings 24 formed integral with the end of the reproducer arm [5. The side wings enclose the greater portion of the pick-up member l6 and serve to protect it from injury. A conductor cord 2| leads from the electrical pickup head It and may be connected with any suitable electrical amplifying means, not shown.

In order to limit the downward swinging of the pick-uphead It about its horizontal aids, and also to'cause it to function with a ,cushion effect, provision is made of a Z-shaped arm 22 projecting rearwardly from the pick-up member I6. As shown in Fig 2, the upper horizontal section of the arm 22 is located adjacent the base of' the channeled reproducer arm l5, and engages the same whenever the arm Ills lifted. a The clockwise rotation of the pick-up I about its axis is one end by means of a bifurcated hanger bracket opposed by a relatively light flat leaf-spring 28 engaging the outer end of the pick-up I4; and anchored to thebase of the channel arm l5, as by rivets. The tension of the spring 23 may be varied by means of an adjustable set screw 24 threadedly engaged in the base of the arm II.

In order to permit the reproducer arm I! .to. swing on both horizontal and verticalaxes, pro-- vision is made of a hollow hub 25 aillxedto the top of the motor panel I0, as by screws 26. The hub supports a ball-bearing raceway 21 within which is mounted a vertical spindle 28 having an enlarged upper split head 29. A pair of opposed set screws 38 are adJustably mounted in the opposite sides of, the arm l5, and have pointed inner ends 80a adapted toengage in pivot sockets 30b carried by the opposite parts of the enlarged head 29 of the spindle 28. I

In order to support the reproducer arm- II at any desired angular position, provision is made of a horizontal arm 3! rigidly secured to the enlarged split head 29, and adapted to swing with the spindle 28. The outer end of the supporting arm 3| is provided with an adjustable set screw 32 which is adapted to engage the underside of scale 35 located on the outer edge of the panel ll for indicating the exact position of the needle arm with respect to the disc record II. A suitable light source, not shown, may be positioned underneath the panel I l to illuminate the pointer lick-up lifting and resetting mechanism The means for raising and lowering the needle with respect to the disc record is clearly shown in V bottom of the reproducer arm 15 at a point slightly in advance .of the set screw 32. The rear end 38 of the lifting arm 36 is bifurcated and carries a pair of inwardly directed pivot screws 39 which ing from a circular ring 4| rotatably seated inan annular groove 42 formed in the upper partof the hub 25. The ring 4| is retained in position by The pick-up member is pivoted on a pair of 7 a cover (use In-order to simultaneously elevate and shift the reproducer arm and needle-carrying pick-up backwardly whenever desired, provision is made of a vertical rod 43 dependingfrom the support I! of the -T-shaped lifting arm 38 to which it is secured by means of a set screw 43a. The rod 43 passes downwardly through a hole 44 in the panel II, and the lower end of said rod engages a spoolshaped cam v45 located therebeneath, said cam 45 comprising a central body 48 and a pair of circular end flanges 41 and 48. The spool cm 4! is mounted eccentrically on a horizontal cam shaft 4!, which is adapted to be rotated onehalf a revolution to lift the pick-up from the record, and another half rotation whenever it is'desired to replace the pick-up upon the record in the predetermined back-spaced position.

, The'horizontal cam shaft 4! is supported at I0. attached to the underside of the panel II. The opposite end of the cam shaft 4! is supported and driven by a suitable electric motor II cannected to -said shaft 40 through a flexible coui-.

pling I2. The motor I is started by the footactuation of an electric switch 58 shown diagrammatically in Fig. 1, said switch being normally held open by a spring 68a. 'The momentary closing of the switch 53 in turn closes a relay switch 69 in the motor. circuit, as will be more fully described later.

The left-hand flange 41 of the spool cam 45, as viewed in Figs. 3 and 5, is formed with semicircular high and low cam sectors 54 and 55, respectively, which are adapted to press laterally upon the lower end of the plunger rod 43.-

The number of grooves of the record to be replayed is controlled by the position of a horizontal adjustable stop shaft 56 located at one side of the plunger rod 43 above the table, as shown in Fig. 3. The stop shaft 56 is threaded intermediate its ends and is screwed into a supporting bracket 51 attached, as by screws, to the top of the cabinet top l6 (see Fig. 1). -The outer end of the stop shaft 56 carries a graduated knurled knob 58 having a pointer 59 which is adapted to register with a graduated stationary dial 66 attached to the bracket 51 for indicating the number of grooves to be repeated. The distance beset to replay any desired smaller number of tween the high and low cam surfaces 54 and 55, respectively, of the flange 41 determines the maximum number of grooves which may be replayed, and it will be understood that the device may be grooves merely by turning the knob 58 to the proper indication on the dial 66. The vertical plunger rod 43 is constantly urged in the direction of the stop member 56, or to the left, as viewed in Figs. 1 and 3, by means of a coiledtension spring 6| connected to the stationary bracket 51 and the movable lifter arm 36.

Automatic motor shut-050 The electrical hook-up for the back spacing mechanism is shown diagrammatically at the bottom of Fig. 1. Thus, the motor 5| is supplied with current by a pair of main circuit conductors 62 and 63, the conductor 63 leading directly to one terminal of the motor 5| while the conductor secondary terminals of a transformer 66 by means of a pair of conductors 61 and 68, the latter conductor having the foot-controlled switch 53' in series therewith.

When the switch 53 is momentarily closed, the magnet 65 will be energized, lifting the armature 68a, closing the relay switch 69, and starting the motor 5|. Current will then continue to fiow through the motor circuit regardless of the fact that the switch 53 is open until the circuit through a conductive commutator drum 16 and conductors 1| and 12 is broken by a quarter revolution of the cam shaft 49. The drum 16 is mounted to rotate with the cam shaft 49 and carries a pair of diametrically opposed insulation.

nubs 13 and 14 which are adapted to rotate into the path of a resilient conductive wiper strip 15 connected to the conductor 12. A second wiper strip 16 engages the surface of the drum 16 at all times. Normally, the nubs 15 and 16 are in tatordrum 16, thus momentarily deenergizing the magnet 65 and opening the motor circuit. The deenergized motor will, however, continue to rotate under its momentum until the nubs 13 and 14 have reached a point 180-degrees from the original dotted linepositions shown lnFlg. 4.

Operation In the operation of "the invention, the reproducer arm l5 will first be swung out over the constantly rotating record, and the needle |1 manually placed in the desired groove. Whenever the operator wishes to repeat any portion of the record, the needle l1 will be lifted from the record and replaced in the desired groove by the operations of twice momentarily closing the footoperated switch 53. The first time the switch 53 is closed, the spool cam 45 will be rotated 90 degrees by the operation of the motor 5| and a further 90 degrees by momentum, causing the plunger 43 to be raised and at the same time laterally shifted backwardly by the action of the eccentric central body 46 and the high sector 54' of the side flange 41 of the spool cam. The needle will thus be automatically back-spaced the desired number of grooves, as indicated by the position of the pointer 59 with respect to the dial plate 66. In order to replace the needle upon the record in the proper back-spaced groove, it will only 0nd time. This will cause another half rotation of the cam shaft 49 in a mannersimilar to that described above, and the return of the cam body 46 to its"low position will cause the needle to be deposited gently upon the record.

Modified form Fig. 6 illustrates a modified form of automatic circuit breaker which may be used in place of the commutator 16 of the first form. In this modified form, the vertical reciprocating movement of the plunger rod 43 is utilized for interleaf-spring 19, on the end ofwhich is a movable switch button 86 located between a pair of stationary contacts 8| and 82 carried by an insulating U-shaped clip 83. The lower contact 8| is electrically connected to the conductor 1|, while the upper contact 82 is afiixed to the end of a set screw 84 having threaded engagement with the upper leg of the clip 83 for permitting said contact 82 to be adjusted relative to the contact 6|. The U-shaped clip 83 is adapted to be supported in an elevated position above the table I6 by means of an angle bracket 85.

In the operation of the modified form of the invention, the position of the collar 11 with respect to the stationary contacts 8| and 82 is such that the plunger rod 43 will make its complete up stroke before the circuit will open between the contacts 86 and 8| for deenergizing the relay magnet 65. The down stroke of said plunger rod 43 will be eifected by the momentum of the mo tor 5|, as before.

While there have been disclosed in this specification.two forms in wh ch the invention may be embodied, it is to be understood that these forms are shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosures but may be modified and embodied in various other forms without departing from its spirit. In short, the invention includes all the modifications and embodibe necessary to foot-actuate the switch 53 a secis claimed as new and for which it is desired to secure Letters Patent, is:

1. In a device for reproducing a disc phonograph record, an elongated universally mounted reproducer arm adapted to swing across vsaid rec- 'ord, a pick-up needle-carrying member flexibly mounted on said arm to swing up and down with respect thereto, means for lifting said arm and pick-up member at will from any point they;

have reached on said record and automatically moving said arm back a predetermined number of grooves, means for thereafter causing said needle to be replaced on said record in backspaced'position on a lateral manual operation, and means to vary the number of grooves of backspacing.

2. In a device for reproducing a, disc phonograph record, an elongated universally mounted reproducer arm adapted to swing across said record, a pick-up needle-carrying member mounted to swing up and down on the end of said arm, a cam, manually controlled means to cause said cam to lift said arm and pick-up member from any point they may have reached on said record and automatically move said pick-up back a predetermined number of grooves, manuallyactuated means to cause said cam to replace said needle on said record in the desired back-spaced position, and means to adjust the amount of the back-spacing.

In a device for reproducing a disc phonog r ph record, an-elongated universally mounted reproducer arm adapted to swingacross said rec-' ord, a'pick-up needle-carrying member mounted to swing up and down on the end of said arm, motor driven cam means, manually actuated means to cause' said cam to lift said arm and pick-up member from said record at any desired. point in their travel across it and automatically swing said pick-up back a predetermined number of grooves, means adapted to be subsequently manually actuated to cause said cam means to replace said needle on saidrecord in the desired back-spacedgroove, and means to adjust the amount of the back-spacing.

4. In a device for reproducing a disc'phonograph record, an elongated universally mounted reproducer arm adapted to swing across said record, a pick-up needle-carrying member mounted to swing up and down on the end of said arm,

switch-operated motor-driven cam means, manually controlled means to cause said cam to lift said arm and pick-up member from said record at any desired point in their travel across it, automatically swinging said arm back a predetermined number of grooves upon one actuation of said switch, and means to cause said cam to replace. said needle on said record in the desired back spaced groove on a subsequent actuation of.

said switch.

5. In a device for reproducing a disc phone graph record, a base, an elongated universally swinging reproducer arm mounted on said base.

' apeedle-carrying pick-up pivoted on a horizontal axis on the end of said arm, a manually controlled auxiliary arm pivotally connected to said base for lifting said reproducer arm and pick-up away from said record whenever desired in the course of their travel across it, said auxiliary arm having an arcuate T-shaped extremity to engage said reproducer arm at any point of its swing.

6. In a device for reproducing a disc phonograph record, a base, an elongated universally swinging reproducer arm mounted on said base, a needle-carrying pick-up pivoted on a horizontal axis on the end of said arm, manually controlled auxiliary arm pivotally connected to said base for lifting said reproducer arm and pick-up away from said record whenever desired in the course of their travel across it, said auxiliary arm being mounted to engage said reproducer arm at any point of 'it's swing, a cam shaft under said base, said auxiliary arm having a depending rod, a cam on said cam shaft engagin said rod for alternately raising and then lowering and laterally back-spacing said reproducer arm, a mo tor for driving said cam shaft, and means for stopping said motor at the expiration of a deflnite rotation of said shaft.

7. In a device for reproducing a disc phonograph record, an elongated pick-up carrying reproducer arm mounted to swing across said recrd, manually controlled means for lifting said arm and pick-up from said record at any desired point they may have reached and automatically moving said pick-up back a predetermined number of grooves, means for thereafter causing said pick-up to be automatically replaced upon said record in back-spaced position, and means to adjust the amount of the back-spacing.'

8. In a device for reproducing a disc phonograph record, an elongated pick-up carrying reproducer arm'mounted to swing across said record, manually actuated means for lifting said arm and pick-up from said record at any desired groove they may have reached, and means operated by a subsequent actuation of said first means for thereafter automatically causing said pick-up to be replaced upon said record.

9. In a device for repr ucing a disc phonograph record, an elonga universally mounted pick-up carrying reproducer arm adapted to swing across said record, a manually controlled auxiliary arm located under said reproducer arm for lifting said reproducer arm and pick-up away from said record whenever desired at the will of the operator, said auxiliary arm having a T-shaped extremity to engage said reproducer arm at any point of its swing.

10. In a device for reproducing a disc phonograph' record; an elongated universally mounted pick-up carrying reproducer arm adapted to swing across said record, manually controlled motor driven rotary cam means to lift said reproducer arm and pick-up from said record whenever desired at the will of the operator, a relay switch in said motor circuit, a normally open mentum' of said motor and cam means being of said cam means to open said independent ,switch and break the motor circuit, the mosumcient to cause said cam means to rotate fur- Y ther and close said independent switch.

LINCOLN THOMPSON. ROBERT L. STONE. 

